Bright nickel plating bath containing a pyridinium or quinolinium phosphate brightener and method of electroplating therewith



United States Patent 3,170,854 BRIGHT NICKEL PLATING BATH CONTAINING A PYRIDINIUM 0R QUINOLINIUM PHOSPHATE BRIGHTENER AND METHOD OF ELECTRO- PLATING THEREWITH Harry Kroll, Kent County, R.I., assignor to Sarki Research and Development Corporation, a corporation of Rhode Island No Drawing. Filed Mar. 18, 1963, Ser. No. 266,063 11 Claims. (Cl. 204-49) (R) n (R)..

N o N 0 R \(H)P(OR)Q R O-i (OR)2 Pyridinium compounds quinolinium compounds R (R) n \g P (ORM Isoquinolinium compoimds In the above representations, R is an aliphatic group saturated or unsaturated, having from one to four carbon atoms, for example, methyl, ethyl, propyl, butyl, allyl and methallyl, R may be hydrogen, i.e., no substituent 'on the ring, or an aliphatic group of one or two carbon atoms, such as methyl, ethyl, or vinyl, and may be substituted in any position of the pyridine, quinoline, or isoquinoline ring or rings. Of outstanding utility are the N-allyl quinaldinium diallyl phosphate, N-allyl 2-vinylpyridinium diallyl phosphate, N-ethyl isoquinolinium diethyl phosphate, N-butyl 4-vinyl pyridinium dibutyl phosphate, and mixtures of the pyridinium and quinolinium and quinaldinium N-alkyl dialkyl phosphates. It should be noted that Z-methylquinoline is quinaldine and the nomenclature herein reflects this in use of quinaldinium to identify the 2-methyl quinoline moiety.

The organic derivatives which are the basis of this invention and the preferred concentrations at which they are used in electroplating baths are listed in Table I. They are used jointly with the sulfur compounds described in Table II. The sulfur compounds listed are a representative group useful for the purpose.

Although quaternary ammonium salts of nitrogen heterocyclics have been previously identified as useful additives to bright nickel plating baths, dialkyl phosphate salts of the N-alkyl pyridinium, quinolinium, isoquinolinium and quinaldinium salts are unique for this application and are also unreported as compounds.

The current conventional practice in employing a quaternized nitrogen heterocyclic for a bright nickel plating bath is to choose a compound in which the anion is Patented Feb. 23, 1965 derived from a water soluble inorganic acid, such as chloride, bromide, sulfate, etc., which forms soluble nickel salts.

about 125 to 225, and if the nitrogen in the cation is quaternized with an alkyl group of the same chemical structure as the alkyl group in the dialkyl ortho phosphate anion, a product is obtained which is water dispersible and produces a superior brilliant adherent nickel deposit when added to a nickel electroplating bath containing the organic additives described in Table II.

The use of the compounds in accordance with this invention for producing bright nickel deposits is based on electrodepositing nickel from a solution of one or more nickel salts to which there has been added 0.005 to 0.30 gram per liter of an N-alkylpyridinium, quinolinium, quinaldinium, or isoquinolinium dialkyl phosphate (see Table I herein) together with 0.1 to grams per liter of a water soluble sulfur compound in which the sulfur atom has a valence of +4 or +6, and is selected from the group of aliphatic unsaturated sulfonic acids, mononuclear and binuclear aromatic sulfonic acids, heterocyclic sulfonic acids, mononuclear aromatic sulfinic acids, aromatic sulfonamides and sulfonimides (see Table II herein). The water soluble alkali metal, ammonium, magnesium, and nickel salts of the above compounds are used in combination with the quaternary nitrogen cyclic compounds in accordance with this invention.

The brightener additives used in the method of this invention were evaluated in a Hull cell using a standard Watts type bath containing 330 grams of nickel sulfate hexahydrate/liter, 45 grams of nickel chloride per liter, 37.5 grams per liter of boric acid, operated at a pH of 3.5, and a temperature of 50 C. The nickel deposits were made on brass Hull cell panels 2" by 3" by plating for five minutes at three amperes. The concentrations and combination of organic additives which gave brilliant mirror-like deposits of nickel over a wide current density range are listed in Table III.

Lustrous and adherent nickel deposits were also obtained from baths having the following composition.

Bath No. 1:

N-allyl quinaldinium diallyl phosphate 0.005-.10 2,5 naphthalene disulfonic acid 2.0-8.0

The above plating bath compositions are illustrative of the ranges of bath compositions which have been tested successfully and do not indicate any limit of the bath composition which can be employed in accordance with the invention. Actually useful ranges of nickel concentration are from 200400 grams per liter; whether the nickel be present in sulfate, chloride nitrateor fluoborate.

The concentrations of the organic sulfur additives and the nitrogen heterocyclic additives listed in the tables are by no means limiting. Preferred operative ranges are given. A considerable variation in concentration of these agents is permissible depending on what the specifications require of the electrodeposited nickel; i.e., brightness, ductility, thickness, speed of build-up, etc.

It is also well understood in the process of bright nickel electroplating that in order to obtain pit-free nickel deposits, it is advantageous to employ agitated, well-filtered solutions. The use of a wetting agent such as sodium lauryl sulfate at concentrations up to 0.25 gram per liter also permits the electroplating of pit-free nickel deposits.

The synthesis of these novel brighteners is readily carried out in accordance with the following procedure:

EXAMPLE I Allyl quinaldinium diallyl phosphate Procedure: The triallyl phosphate and quinaldine are mixed together, and carefully heated to 65 C. The temperature is allowed to rise slowly to 120 C. This is accomplished by shutting of the heating mantles at -10 degree intervals, and allowing the temperature to rise due to the exothermic contribution of the reaction. When the temperature reaches 120 C., and the exothermic phase of the reaction is completed, the temperature is raised to 130 C., and held at this point for twelve hours.

To determine the point of completion of the reaction, a 1 gram sample is removed and titrated potentiometrically using a glass-calomel electrode system, and an ethylene glycolisopropanol solvent system.

The pyridine compounds are synthesized in the same fashion. The trialkyl phosphate ester is reacted with the appropriate pyridine in stoichiometric proportions and the quaternized compound recovered. Thus trimethyl, triethyl, tripropyl, tributyl, triallyl or trimethallyl phosphate is reacted, as in Example I, in a 1:1 molar ratio to make the corresponding quaternized compound.

EXAMPLE II To synthesize the methallyl quinaldinium dimethallyl phosphate, the trimethallyl ester is reacted with quinoline under the conditions described in Example I.

EXAMPLE III To make the propyl quinaldinium dipropyl phosphate, the tripropyl posphate is reacted with the quinoline as in Example I.

EXAMPLE IV Similarly, for making the methyl, ethyl and butyl compounds, the corresponding trialkyl phosphates are reacted with the quinoline.

In other words, the synthesis is the direct stoichiometric reaction carried out carefully with stoichiometric amounts, so that a good yield is obtained.

Referring to the following tables, in Table I, I have listed certain of the preferred quaternized pyridine, quinoline and isoquinoline compounds useful for addition to conventional plating baths as brighteners. It have also indicated the preferred range of concentration.

In Table II, I have listed a group of preferred sulfur compounds which are commonly referred to in the trade as primary brighteners. By this, is meant that they are added to the plating bath as brighteners and with the cyclic nitrogen compounds give a net result which is a substantial improvement over the effect obtained with either one alone. The preferred concentration ranges are also indicated.

Any of the primary brighteners listed in Table II as being typical may be combined with any of the secondary brighteners of Table I in the conventional acid nickel plating baths. I have tested a large variety of combinations, virtually exhausting the possibilities, and have found that, in all cases, an improvement in the brightening effect is obtained. In Table III, I have listed certain of the preferred combinations, indicating that in any of the conventional Watts type baths used in the art, or conforming to those indicated herein, the combination will produce optimum results. Here, it will be noted that in some cases there are two sulfur compounds where pyridine, quinoline and isoquinoline components are used. In all cases, the results are characterized by the fact that improvements in brighteners, adherence, ductility are obtained under ordinary nickel plating conditions.

TABLE I Compound: Concentration range, grams/liter (1) N-allyl pyridinium diallyl phosphate 0.00l-.10 (2) N-2-methallyl pyridinium dimethyl phosphate 0.001-.10 (3) N-propyl 2-methyl pyridinium dipropyl phosphate 0.001.10 (4) N-allyl 2-vinyl pyridinium diallyl phosphate 0.001.l0 (5) N-allyl 4-vinyl pyridinium diallyl phospate 0.001.l0 (6) N-allyl 2-methyl quinolinium diallyl phospate 0.001.l0 (7) N-propyl Z-methyl quinolinium dipropyl phosphate 0.00l-.l0 (8) N-butyl quinolinium dibutyl phosphate 0.00l-.10 (9) N-methallyl quinolinium dimethallyl phosphate 0.00l-.l0 (10) N-propyl quinolinium dipropyl phosphate 0.00l-.10 (11) N-allyl isoquinolinium diallyl phosphate 0.00l.10 (l2) N-methallyl isoquinolinium dimethallyl phosphate 0.001.l0 (13) N-butyl isoquinolinium dibutyl phosphate 0.001-.10 (14) N-propyl isoquinolinium dipropyl phosphate 0.001-.10 (15) N-ethyl isoquinolinium diethyl phosphate 0.00l.l0

TABLE II Organic sulfur additives Compound: Concentration range, grams/liter Benzene sulfonamide 0.1-3 P-toluenesulfonamide 0.1-2 O-benzoylsulfonimide 0.1-1.5 O-carboxybenezesulfonamide 0.1-2.0 Benzene sulfohydroxamic acid 0.1-2.0 N-benzenesulfonyl iminodiacetic acid 0.12.0 N-benzenesulfonyl iminodipropionic acid 0.l-2.0 Allyl sulfonic acid l-l0 Vinyl sulfonic acid 1-10 Sodium benzenesulfonate l-10.0 Sodium metabenzenedisulfonate l-10.0 1,5 naphthalene disulfonic acid l-8 2,7 naphthalene disulfonic acid l-8 Naphthalene trisulfonic acid 1-8 5 TABLE 111 Bath No. Grams/ Addition Agents 4 l a liter Para toluenesnlfnnamida N -Butyl Z-methylquinolinium dibutyl phos- 2 phate o-Benzoyl sulfonimide {N-methallyl quinolinium dimethallyl phosphate Benzenesulfonamide o-Benzoylsulfonimide {N -a1lyl 2-vinylpyridinilln1 Benzene sulfonamide o-Benzoylsultonirnide {N-allyl 4-vinyl pyridinium phosphate o :00 oosco Q0 05 o-Benzoylsulfommide Para toluenesulionamide {Nethyl isoquinolinium diethyl phosphate 6 Para tnlnenesnlfnnamide o-benzoyl sulfonimide 7 N -propyl 2-vinylpyridinium dipropyl phosphate o-Benzoyl sulfonimide N -allyl 2-methylquinolinium diallyl phosphate Allyl sulfonic acid 9 {N-allyl lmethylquinolinium diall phosphate Naphthalene trisulfonie acid 10 N -allyl 2-methylquino1inium diallyl phosphate" Benzenesulfonate, sodium salt What is claimed is:

1. A bath for producing bright nickel deposits comprising an aqueous acid solution of at least one soluble nickel salt, 0.2 to 50 grams per liter of at least one organic sulfur compound selected from the group consisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, aromatic sulfonamides and sulfinimides, and 0.001 to 0.30 gram per liter of at least one compound selected from the group consisting of:

where R is selected from the group consisting of saturated and unsaturated aliphatic radicals having from l'tov 4 carbon atoms, R is selected from the group consisting of methyl, ethyl, and vinyl groups, and n has a value of 0-1.

2. A bath for producing bright nickel deposits comprising an aqueous acid solution of nickel sulfate and nickel chloride, and 0.20 to 50 grams per liter of at least one organic sulfur compound selected from the group consisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, aromatic sulfonamides and sulfonimides, and 0.001 to 0.30 gram per liter of at least one compound selected from the group consisting of:

where R is selected from ,the group consisting of saturated and unsaturated aliphatic radicals having from 1 to 4 carbon atoms, and R is selected from the group consisting of methyl, ethyl, vinyl, and n has a value of 041.

3. A bath for producing bright nickel deposits comprising an aqueous acid solution of nickel sulfate and nickel chloride, and 0.20 to 50 gramsper liter of at least one organic sulfur compound selected from the 'group consisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, and aromatic sulfonamides and sulfonimides, and 0.001 to 030 gram per liter of N-allyl 2- methyl quinolinium diallyl phosphate.

4. A bath for producing bright nickel deposits comprising an aqueous acid solution of nickel sulfate and nickel chloride, and 0.20 to 50 grams per liter of at least one organic sulfur compound selected from the group consisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, and aromatic sulfonamides and sulfonimides, and 0.001 to 0.30 gram per liter of N-allyl quinolinium diallyl phosphate.

5. Abath for producing bright nickel deposits comprising an aqueous acid solution of nickel sulfate and nickel chloride and 0.20 to 50 grams per liter of at least one organic sulfur compound selected from the group consisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, and aromatic sulfonamides and sulfonimides, and 0.001 to 0.30 gram per liter of N-allyl 2-vinyl pyridinium diallyl phosphate.

6. A bath for producing bright nickel deposits comprising an aqueous acid solution of nickel sulfate and nickel chloride, and 0.20 to 50' grams per liter of at least one organic sulfur compound selected from the group con sisting of unsaturated aliphatic sulfonic acids, aromatic sulfonic acids, and aromatic sulfonamides and sulfonimides, and 0.001 to 0.30 gram per liter N-allyl 4-viny1 pyridinium diallyl phosphate.

7. The method of electroplating nickel on a metal base to develop a deposit having brilliant luster, high ductility and good level of adherence which comprises maintaining in an acid aqueous'nickel plating bath an organic sulfur compound brightener, in the range from 0.10 gram to about 10 grams per liter, and at least one compound as a primary brightener selected from the group consisting of h V 05mm b: a on )1 i i t R OP(OR)g R O-P-(OR);

wherein R is selected from the group consisting of saturated and unsaturated radicals having from one to four carbon atoms; R is selected from the group consisting of methyl, ethyl and vinyl, and n has a value of 0-1, the amount of brightener being in the range from 0.001 gram per liter to saturation, while submerging the article to be plated in said bath and passing a current through said bath, the article being the cathode.

8. The method in accordance with claim 7 in which the said brightener is N-allyl quinolinium diallyl phosphate.

.9. The method in accordance with claim 7 in which the said brightener is N-allyl 2-vinyl pyridinium phosphate.

10. The method in accordance with claim 7 in which the said brightener is N-allyl 4-vinyl pyridinium diallyl phosphate.

11. The method in accordance with claim 7 in which the said brightener is N-allyl Z-methyl quinolinium diallyl phosphate.

References Cited by the Examiner UNITED STATES PATENTS 6/56 Cislak 260-290 8 Haas et a1. 20449 Stehman 260--290 Heiling 20449 Strauss et a1 20449 JOHN H. MACK, Primary Examiner.

MURRAY TILLMAN, Examiner. 

1. A BATH FOR PRODUCING BRIGHT NICKEL DEPOSITS COMPRISING AN AQUEOUS ACID SOLUTION OF AT LEAST ONE SOLUBLE NICKEL SALT, 0.2 TO 50 GRAMS PER LITER OF AT LEAST ONE ORGANIC SULFUR COMPOUND SELECTED FROM THE GROUP CONSISTING OF UNSATURATED ALIPHATIC SULFONIC ACIDS, AROMATIC SULFONIC ACIDS, AROMATIC SULFONAMIDES AND SULFINIMIDES, AND 0.001 TO 0.30 GRAM PER LITER OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF: 